Mercurial > trustbridge
comparison common/linuxlockfile.c @ 782:20ca94680003
Implemented detection of running instance on linux using a lock file.
| author | Sascha Wilde <wilde@intevation.de> |
|---|---|
| date | Mon, 14 Jul 2014 12:46:47 +0200 |
| parents | |
| children | a974b61a5cce |
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| 773:2c69298b4188 | 782:20ca94680003 |
|---|---|
| 1 #ifndef WIN32 | |
| 2 | |
| 3 #include <fcntl.h> | |
| 4 #include <stdio.h> | |
| 5 #include <sys/types.h> | |
| 6 #include <unistd.h> | |
| 7 | |
| 8 #include "logging.h" | |
| 9 | |
| 10 int | |
| 11 open_lockfile(char *path) | |
| 12 { | |
| 13 int fd; | |
| 14 char pidstr[20]; | |
| 15 size_t pidstrlen; | |
| 16 struct flock lk; | |
| 17 fd = open(path, O_RDWR | O_CREAT, 0600); | |
| 18 if (fd != -1) | |
| 19 { | |
| 20 /* Get an exclusive lock on the whole file. */ | |
| 21 lk.l_type = F_WRLCK; | |
| 22 lk.l_whence = SEEK_SET; | |
| 23 lk.l_start = 0; | |
| 24 lk.l_len = 0; | |
| 25 if (fcntl(fd, F_SETLK, &lk) != -1) | |
| 26 { | |
| 27 /* FIXME: For extra security we should check if there is | |
| 28 already a pid in the file. If so we should check in | |
| 29 /proc/$PID if there is still a process of the same name | |
| 30 as ours running... */ | |
| 31 ftruncate(fd, 0); | |
| 32 pidstrlen = (size_t)snprintf(pidstr, sizeof(pidstr), "%d", getpid()); | |
| 33 write(fd, pidstr, pidstrlen); | |
| 34 } | |
| 35 else | |
| 36 { | |
| 37 /* Lock can not be acquired. Bail out... */ | |
| 38 close(fd); | |
| 39 DEBUGPRINTF("Could not get an exclusive lock on %s.\n", path); | |
| 40 return -1; | |
| 41 } | |
| 42 } | |
| 43 else | |
| 44 { | |
| 45 DEBUGPRINTF("Failed to open lock file: %s.\n", path); | |
| 46 } | |
| 47 return fd; | |
| 48 } | |
| 49 | |
| 50 void | |
| 51 close_lockfile(int fd) | |
| 52 { | |
| 53 struct flock lk; | |
| 54 | |
| 55 /* Delete the PID from file. */ | |
| 56 /* We do this instead of trying to unlink the file. */ | |
| 57 ftruncate(fd, 0); | |
| 58 | |
| 59 /* Remove lock from the file. */ | |
| 60 lk.l_type = F_UNLCK; | |
| 61 lk.l_whence = SEEK_SET; | |
| 62 lk.l_start = 0; | |
| 63 lk.l_len = 0; | |
| 64 if (fcntl(fd, F_SETLK, &lk) == -1) | |
| 65 { | |
| 66 /* Lock can not be removed?!? WTF? */ | |
| 67 DEBUGPRINTF("Could not remove lock from pid file. STRANGE!\n"); | |
| 68 } | |
| 69 close(fd); | |
| 70 } | |
| 71 | |
| 72 #endif /* Not WIN32 */ |